50 Pesetas Banco de España - Bilbao

Bilbao's Republican currency during the Spanish Civil War had a short window of relevance. The city fell to Nationalist forces in June 1937, and the notes issued by the Basque regional government's banking apparatus — operating under the Banco de España name but functionally autonomous — became worthless almost immediately. This series was printed locally by Arte y Editorial Vasca, an arrangement born of necessity rather than preference, as access to Spain's conventional printing infrastructure had been severed by the war.

The brevity of circulation means heavily used examples are actually harder to explain than uncirculated ones.